class_docstr: Create an object holding a new letterboxed image as `image` attribute.
  
  Letterboxing is defined as scaling the input image to fit inside the
  desired output image frame (letterbox) while preserving the aspect
  ratio of the original image. The pixels that are not filled with the
  original image pixels become 127.
  
  The created object also provides a functionality to convert bounding box
  coordinates back to the original image frame.
  
  Args:
  
      image (numpy.ndarray): An uint8 3-channel image 
      height (int): Letterbox height
      width (int): Letterbox width
docstr: Convert the bounding boxes back to the original image frame.
  
  Args:
      coords (numpy.ndarray):
          `N` x `M` array where `M >= 4` and first 4 elements
          of `M` are `x`, `y` (center coordinates of bounding box),
          `w` and `h` (bouding box width and height).
docstr_tok: ["Convert","the","bounding","boxes","back","to","the","original","image","frame",".","Args",":","coords","(","numpy.ndarray",")",":","`","N","`","x","`","M","`","array","where","`","M",">","=","4","`","and","first","4","elements","of","`","M","`","are","`","x","`",",","`","y","`","(","center","coordinates","of","bounding","box",")",",","`","w","`","and","`","h","`","(","bouding","box","width","and","height",")","."]
code: def inverse_coordinate_transform(self, coords):
      """Convert the bounding boxes back to the original image frame.
  
      Args:
          coords (numpy.ndarray):
              `N` x `M` array where `M >= 4` and first 4 elements
              of `M` are `x`, `y` (center coordinates of bounding box),
              `w` and `h` (bouding box width and height).
  
      """
      return apply_inverse_letterbox_coordinate_transform(
          coords,
          self.im_w,
          self.im_h,
          self.new_w * 1.0 / self.width,
          self.new_h * 1.0 / self.height,
      )
  
file_path: nnabla/python/src/nnabla/models/object_detection/utils.py
imports: import numpy
  from nnabla.models.object_detection.draw_utils import DrawBoundingBoxes
  from nnabla.utils.image_utils import imresize
label_desc: Use image node_id 2 for calling the LetterBoxTransform obj's underlying member method code with example usage: obj.inverse_coordinate_transform(coords) and returns: apply_inverse_letterbox_coordinate_transform